Process for dispersing organic pigments with ultrasonic radiation

ABSTRACT

Dispersions of organic pigments are produced by adding a surfactant to an aqueous slurry of an organic pigment followed by subjecting the slurry to ultrasonic radiation. The surfactant utilized is one or more of the surfactants selected from the group consisting of: various specific acidic or quaternary salts of alkyl substituted propanediamines, and derivatives thereof, as well as a poly(ethyleneoxide) ether of an 18 carbon alcohol having 9 units of ethylene oxide thereon.

This application is a continuation-in-part of application Ser. No.07/312,870, filed Feb. 21, 1989, now U.S. Pat. No. 4,929,279.

The present invention pertains to a process for making dispersions ofparticulate materials. More specifically, the invention relates todispersing organic pigments. The method utilized ultrasonic energy incombination with specific organic dispersing agents.

Several U.S. patents are related to the present invention. Below is adiscussion of the most closely related patents presently known to theinventor.

U.S. Pat. No. 4,665,107 (hereinafter the '107 patent) describes a methodfor producing a colorant comprising a stable aqueous suspension byemulsifying a mixture of (a) an organic solvent, (b) a polymer solublein the organic solvent, and (c) a pigment, the mixture of (a)-(c) beingemulsified in water containing a surfactant. In the '107 patent, thepigment is dispersed in the organic solvent with an ultrasonic probe.The pigment/organic solvent mixture is then combined with awater/surfactant mixture and an emulsion of the organic solvent mixtureis made using the ultrasonic probe. The '107 patent mentions a varietyof surfactants, including Aerosol OT-75, Surfynol TG, Katapone VV, AonylFSN, Span 60, Lipal 4LA, and lecithin. In contrast to the '107 patent,the process of the present invention utilizes one or more members of agroup of surfactants, the members of this group being different from thesurfactants listed in the '107 patent. In further contrast to the '107patent, the process of the present invention does not require the use ofa solvent.

U.S. Pat. No. 4,701,218 (hereinafter the '208 patent) relates to bothdry, free-flowing floccular compositions of ultrafine particles as wellas to a method of making free-flowing floccular compositions ofultrafine particles. The method may utilize any of a large group ofsurfactants including non-ionics, anionics or cationics (see column 3,lines 21-27), and the collodial dispersion of the particles may be madeby a variety of conventional agitation techniques, such as ultrasonicvibrations and rapid stirring. In contrast to the '218 patent, theprocess of the present invention requires that one or more of a specificgroup of surfactants be utilized along with ultrasonic dispersion.

U.S. Pat. No. 4,588,576 (hereinafter the '576 patent) relates to aprocess for the production of microcrystalline metal oxide powder byforming a solution of a zirconium metalorganic compound followed bysubjecting the solution to ultrasonic wave energy, etc. Column 4, lines14-19 of the '576 patent state that a surfactant is employed in thesolution forming step, i.e. prior to exposing the solution to ultrasonicradiation. Column 5, lines 33-50 lists a large number of suitablesurfactants, among which listing are quaternary ammonium salts. Thepresent invention differs from the '576 patent in many ways, not theleast of which is that the pigments dispersed in the process of thepresent invention are organic pigments, whereas the pigments mentionedin the '576 patent are inorganic pigments. Furthermore, the process ofthe present invention applies to a specific set of surfactants.

BRIEF SUMMARY OF THE INVENTION

The present invention is a process of dispersing an organic pigment. Themethod is carried out by first adding a surfactant to an aqueous slurryof an organic pigment. The surfactant is at least one member selectedfrom the group consisting of:

1. an acidic salt of N-alkyl-N,N',N'-trimethyl-1,3-propanediamine,wherein the alkyl group contains from about 12 to about 22 carbon atoms,as well as triethyl and tripropyl derivatives thereof;

2. an acidic salt ofN-alkyl-N,N',N'-tris(2-hydroxypropyl)-1,3-propanediamine, wherein thealkyl group contains from about 12 to about 22 carbon atoms, as well as2-hydroxyethyl and 2-hydroxybutyl derivatives thereof;

3. a quaternary salt ofN-alkyl-N,N,N',N',N'-pentamethyl-1,3-propanediamine, wherein the alkylgroup contains from about 12 to about 22 carbon atoms, as well aspentaethyl and pentapropyl derivatives thereof;

4. an acidic salt of N-alkyl-N'-(3-aminopropane)-1,3-propanediamine,wherein the alkyl group contains from about 12 to about 22 carbon atoms,as well as tetramethyl, tetraethyl, tetrapropyl,tetrakis(2-hydroxyethyl), tetrakis(2-hydroxypropyl),tetrakis(2-hydroxybutyl), heptamethyl, heptaethyl, and heptapropylderivatives thereof;

5. an acidic salt of N-alkyl-N-(3-aminopropane)-1,3-propanediamine,wherein the alkyl group contains from about 12 to about 22 carbon atoms,as well as tetramethyl, tetraethyl, tetrapropyl,tetrakis(2-hydroxyethyl), tetrakis(2-hydroxypropyl),tetrakis(2-hydroxybutyl), heptamethyl, heptaethyl, and heptapropylderivatives thereof;

6. the acidic salt ofN-(N-alkyl-3-aminopropane)-N'-(3-aminopropane)-1,3-propanediamine,wherein the alkyl group contains from about 12 to about 22 carbon atoms,as well as pentamethyl, pentaethyl, pentapropyl,pentakis(2-hydroxyethyl), pentakis(2-hydroxypropyl),pentakis(2-hydroxybutyl), nonamethyl, nonaethyl, and nonapropylderivatives thereof;

7. a poly(ethyleneoxide) ether of an 18 carbon alcohol having 9 units ofethylene oxide thereon.

The method of the present invention pertains to the addition of at leastone member (of the above-listed group of surfactants) to an aqueousslurry of an organic pigment, following which the pigment is dispersedby subjecting the slurry to ultrasonic radiation. Most of thesurfactants (i.e. 1 through 7, above) are acidic salts of specificamines as well as salts of derivatives of those amines. These acidicsalts were prepared by stirring and heating the amine in dilute acid, toyield clear solutions. The acids used can include: acetic acid,hydrochloric acid, sulfuric acid, formic acid, and hydrobromic acid. Thepigment is then dispersed by subjecting the slurry to ultrasonicradiation. Numerous surfactants have been tested for effectiveness whenusing ultrasonic irradiation as the method of dispersion, and theabove-named surfactants were unexpectedly found to produce superiorresults. In order to enable the filtration and washing of presscakes,any member within the six categories of amine surfactants (i.e. 1through 6, above) mentioned above would be preferable to the quaternaryammonium salt. The easiest method for deactivation of the quaternaryammonium salt is via precipitation with a large anion (e.g. apolynaphthalene sulfonate/formaldehyde condensate), which adds extraweight and dilutes the strength of the pigment. In contrast, the acidicammonium salts can be deactivated in the acidic pigment slurries byaddition of sufficient alkali. Unlike the addition of a large anion toprecipitate the quaternary ammonium cation, the addition of alkali toneutralize the ammonium salts does not further extend the pigment anddilute the pigment strength. The nonionic surfactant can be deactivatedby addition of the salt (e.g., ammonium or sodium) of a polyacrylic acidor acrylic acid copolymer, followed by addition of sufficient acid.

A member within each of the above seven groups of surfactants is asfollows: (1) Duomeen® TTM isN-tallowalkyl-N,N',N'-trimethyl-1,3-propanediamine; (2) Propoduomeen®T/13 is N-tallowalkyl-N,N',N'-tris(2-hydroxypropyl)-1,3-propanediamine;(3) Duoquad® T-50 isN-tallowalkyl-N,N,N',N',N'-pentamethyl-1,3-propanediamine dichloride (4)Jetamine® TRT is N-tallowalkyl-N'-(3-aminopropane)-1,3-propanediamine;(5) Lilamin® LSP-33 isN-tallowalkyl-N-(3-aminopropane)-1,3-propanediamine; (6) Jetamine® TETisN-(N-tallowalkyl-3-aminopropane)-N'-(3-aminopropane)-1,3-propanediamine;(7) Chemal® OA-9 is a poly(ethyleneoxide) ether of an 18 carbon alcoholhaving 9 units of ethylene oxide thereon.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is highly desirable, when making dispersions of very smallparticulates, to prevent and/or reduce flocculation of the particulatesto as great a degree as possible. In the case of pigments, it isdesirable to prevent flocculation in order to maintain the strength ofthe pigment dispersion as well as to decrease undesirable side effectswhich accompany pigment flocculation, such as "flooding" of inks orpaints containing more than one pigment (e.g. copper phthalocyanine blueand titanium dioxide). The most advantageous result of good pigmentdispersion is retention of high pigment strength. Higher pigmentstrength translates into higher pigment dollar value, as the same massof colored particles, deflocculated to a greater degree, becomes morevaluable per unit mass, because the deflocculated particles impartgreater tinting strength or coloring capacity per unit mass of coloredparticles. As a result, a lesser amount of the higher strength pigmentdispersion can be used to achieve a required level of tinting strengthor coloring capacity.

In order to make a highly deflocculated pigment dispersion, it hasheretofore been necessary to expend large amounts of energy to impart ahigh degree of shear to the pigment flocculates and agglomerates.Generally, the high shear has been imparted by high-powered devices suchas shot mills which grind or otherwise agitate the pigment dispersionwith high energy, or by lower energy devices such as ball mills whichgrind the pigment dispersion for a relatively long time--e.g. 24 to 72or more hours. Ultrasonic irradiation, although generally recognized asa means of pigment dispersion, has not heretofore been recognized as asuperior means of pigment dispersion. The inventor of the presentprocess has unexpectedly discovered that ultrasonic irradiation, whenused in combination with one or more members of a group of surfactants,produces a desired degree of dispersion of pigment in less time, andwith less energy than any other currently known method of pigmentdispersion. Furthermore, this method of dispersion does not requireseparation of the finished dispersion from the grinding media (e.g.,steel shot, sand, pebbles or balls) used in the usual methods ofdispersion.

As described in U.S. Pat. No. 4,588,576, ultrasonic wave energy can beprovided by any conventional system, such as an aqueous bath equippedwith a source of high frequency vibrations. Any acoustic generator canbe employed, e.g. a piezoelectric type generator, a mechanicalgenerator, or a magnetorestrictive type. Generally, ultrasonic radiationincludes frequencies from about 15 kilohertz to about 20,000 kilohertz.The frequency range of between about 15 kilohertz and 3,000 kilohertz isthe most suitable in the process of the present invention. Mostpreferred is the 40-2,000 kilohertz range. In general, the ultrasonicintensity used can be within the range of about 20 watts/cm² and 500watts/cm².

The process of the present invention is applicable to all organicpigments. More specifically, the term organic pigments is meant toinclude nitroso pigments, monoazo pigments, disazo pigments, disazocondensation pigments, basic dye pigments, alkali blue pigments, Peacockblue lake pigments, phloxine pigments, quinacridone pigments, lakepigments of Acid Yellow 1 and 3, carbazole dioxazine violet pigments,alizarine lake pigments, vat pigments, phthalocyanine pigments, carminelake pigments, tetrachloroisoindolinone pigments and carbon blackpigments. Preferably the organic pigment is selected from the groupconsisting of monoazo, disazo, phthalocyanine and carbon black pigments.Most preferably the organic pigment is selected from the groupconsisting of acetoacetanilide (AAA) diarylide yellow (Pigment Yellow12), copper phthalocyanine blue (Pigment Blue 15), carbon black (PigmentBlack 7) and barium Lithol® red (Pigment Red 49).

Examples 1-52 involve the dispersion of AAA Yellow pigments. Examples1-52 each involve the use of a AAA Yellow strike slurry as a startingmaterial. The AAA Yellow strike slurries were prepared as follows.

Tetrazotized 3,3'-dichlorobenzidine (DCB) was prepared by stirring DCBdihydrochloride in an ice/hydrochloric acid slurry with a slightstoichiometric excess of sodium nitrite. The stirring was continued forabout one hour at 0°-5° C. Excess nitrous acid was eliminated withsulfamic acid, giving approximately 0.5 molar DCB tetrazo. 0.25 molarDCB tetrazo was produced by the addition of an equal volume of icewater.

For the statistically designed experiments, sufficient acetoacetanilide(AAA) for four strikes was dissolved in dilute caustic solution, splitinto four equal parts and reprecipitated with acetic acid to pH 6. Forthe pH 6→pH 3.5 strike, a 19:1 molar ratio of sodium acetate:AAA wasused. For constant pH strikes, a 1:1 molar ratio of sodium acetate:AAAwas used, with 10 weight percent sodium hydroxide being addedcontinuously to maintain pH during striking.

In the statistically designed experiments, two strikes were performedsimultaneously, using a Cole-Palmer Masterflex tubing pump, the pumpbeing fitted with two heads and size 14 tubing. The pump was set todeliver 3-4 ml/minute DCB tetrazo at a constant rate. Striking wascontinued until there was only a slight excess of AAA. The strikeslurries were then treated with a 10 weight percent Duoquad® T solution,added at various levels based on the amount of AAA Yellow present afterstriking.

It is preferred that the process of the present invention be carried outusing the surfactant in an amount between 2 percent, on weight ofpigment, and 100 percent, on weight of pigment. It is more preferredthat the surfactant is present in an amount between 5 percent, on weightof pigment, and 85 percent, on weight of pigment. For transparentpigments, it is preferred that the surfactant is present in an amountbetween 10 percent, on weight of pigment, and 30 percent, on weight ofpigment. For opaque pigments it is preferred that the surfactant ispresent in an amount between 5 percent, on weight pigment, and 10percent, on weight of pigment. In contrast, it is preferred that thesurfactant is present in an amount between 50 percent, on weight ofpigment, and 90 percent, on weight of pigment, if the dispersion processis being carried out during the striking of the pigment.

EXAMPLES 1-8 (COMPARATIVE)

Pigment dispersions were made via several methods, for comparativepurposes. A variety of dispersion techniques, other than ultrasonictechniques, are given in Table I, below. Each of the methods utilized inTable I began with a freshly-prepared AAA Diarylide Yellow (PigmentYellow 12) strike slurry which had been treated with 30 percent, basedon weight of pigment, of N-tallow-alkyl-N,N,N',N',N'-pentamethyldichloride. Table I gives dispersion conditions in the middle column,while the right column of Table I indicates the mean diameter (innanometers, nm) of the particulate material in the slurry. The meandiameter was measured by diluting the strike slurry 1:400 with distilledwater, placing the diluted slurry in a sample cuvettes and determiningthe mean diameter with a Coulter Electronics Submicron Particle SizeAnalyzer Model N-4. Three values are listed because the mean diametermeasurement was performed 3 times on each sample, at intervals ofapproximately 4 minutes. The results were printed out on an Axiomprinter. The best combination of high shear mechanical dispersion andoven aging produced mean diameters of about 120 nm.

                  TABLE I                                                         ______________________________________                                        Mean Diameter of AAA Yellow Slurry                                            Dispersed Under Different Conditions                                                                       Mean Diameter                                    Example                                                                              Dispersion Conditions (nm)                                             ______________________________________                                        1      None                  5500                                             2      Boiled for 2 hours    204; 202; 207                                    3      Boiled for 8 hours    164; 167; 173                                    4      Stored at 80° for 16 hours                                                                   180; 176; 178                                    5      Stored at 60° for 16 hours                                                                   141; 158; 166                                    6      Stored at 20° C. for 24 hours, then                                                          245; 247; 249                                           dispersed under high shear in a                                               Kinematica (Kriens-Luzern) CH-6010                                            mixer for two minutes.                                                 7      Same as #6, except stored at 60° C.                                                          121; 125; 132                                           for 24 hours.                                                          8      Same as #6, except stored at 60° C.                                                          125; 133; 145                                           for 96 hours.                                                          ______________________________________                                    

EXAMPLES 9-14

Examples 9-14 illustrate the effects of several conditions fordispersing the AAA Yellow strike slurry (of Examples 1-8) withultrasonic irradiation. In these Examples, the AAA Yellow strike slurrywas treated with 30 percent based on weight of AAA Yellow of Duoquad® T(i.e. N-tallow alkyl-N,N,N',N',N'-pentamethyl-1,3-propanediaminedichloride). About 25 gram aliquots of these slurries were put intoone-ounce jars, which were capped and placed in the ultrasonic devicecontaining some water. Ice was intermittently added to the water inorder to maintain a temperature of 20° C. The ultrasonic device employedwas a 300 W Cole-Palmer Branson Ultrasonic Cleaner Model B-321. As canbe seen in Table II, ultrasonic dispersion at elevated temperature (i.e.60° C.) and for extended periods (i.e. 1.5-4.5 hours) producedrelatively stable dispersions of significantly lower mean diameters(70-100 nm) in comparison with Examples 1-8.

                  TABLE II                                                        ______________________________________                                        Mean Diameters of AAA Yellow Slurry                                           Ultrasonically Dispersed Under Various Conditions                                                          Mean Diameter                                    Example Ultrasonic Dispersion Conditions                                                                   (nm)                                             ______________________________________                                         9      1.5 hours at 20° C.                                                                         257; 305; 338                                    10      1.5 hours at 60° C.                                                                          99; 105; 109                                    11      1.5 hours at 60° C., then stored at                                                         109; 109; 110                                            20° C. for 13 hours                                            12      1.5 hours at 60° C., stored at 20° C.                                                81; 83; 84                                               for 13 hours, then irradiated for                                             1.5 additional hours at 60° C.                                 13      1.5 hours at 60° C., stored at 20° C.                                                75; 76; 77                                               for 48 hours, then irradiated for                                             1.5 additional hours at 60° C.                                 14      1.5 hours at 60° C., stored at 20° C.                                                70; 72; 72                                               for 48 hours, then irradiated for                                             3 additional hours at 60° C.                                   ______________________________________                                    

EXAMPLES 15-23

Examples 15-23 illustrate the effects of post-treating the AAA Yellowstrike slurry with various levels of Duoquad®T and ultrasonicallydispersing the pigmentary material at two elevated temperatures. TableIII provides the level of surfactant, the dispersion conditions, and themean particle diameter after dispersion. In general, Table IIIillustrates that at 60° C. 30 weight percent Duoquad®T produced slightlygreater dispersion (i.e. lower mean diameters) than did 20 weightpercent Duoquad®T or 50 weight percent Duoquad®T. However, at 80° C., 20weight percent Duoquad®T was more effective. Furthermore, Table IIIindicates that ultrasonic dispersion at 60° gave significantly lowermean diameters than ultrasonic dispersion at 80° C. The ultrasonicdispersion method employed was the same as in Examples 9-14, as was themethod for measurement of mean particle diameter.

                  TABLE III                                                       ______________________________________                                        Mean Diameters of AAA Yellow Slurry Treated                                   And Ultrasonically Dispersed Under Various Conditions                                 Treatment                                                                     Level of    Ultrasonic   Mean                                                 Duoquad ® T                                                                           Dispersion   Diameter                                     Example (wt %)      Conditions   (nm)                                         ______________________________________                                        15      20          1.5 hours at 80° C.                                                                 137; 143; 145                                16      20          3.0 hours at 80° C.                                                                 131; 137; 142                                17      20          1.5 hours at 60° C.                                                                 105; 107; 111                                18      30          1.5 hours at 80° C.                                                                 202; 226; 218                                19      30          3.0 hours at 80° C.                                                                 180; 202; 206                                20      30          1.5 hours at 60° C.                                                                  95;  99; 101                                21      50          1.5 hours at 80° C.                                                                 169; 177; 177                                22      50          3.0 hours at 80° C.                                                                 156; 173; 176                                23      50          1.5 hours at 60° C.                                                                 111; 114; 114                                ______________________________________                                    

EXAMPLES 24-30

A freshly-prepared AAA yellow strike slurry was ultrasonically dispersedat different temperatures in order to find an optimum temperature forthe ultrasonic dispersion process. The AAA Yellow strike slurry wastreated with 20 percent (on weight of pigment) of Duoquad®T, followingwhich the slurry/surfactant mixture was stored at 20° for three daysbefore the ultrasonic irradiation was performed. Ultrasonic irradiationwas applied to each of the samples for a period of 1.5 hours withtemperatures being maintained by addition of ice and water. As shown inTable IV, the lowest mean diameter was obtained at 70° C. Just as inExamples 9-14, the ultrasonic device employed was a 300 W Cole-PalmerBranson Ultrasonic Cleaner Model B-321, and the mean particle diameterwas determined with a Coulter Electronics submicron Particle SizeAnalyzer model N-4.

                  TABLE IV                                                        ______________________________________                                        Mean Diameters of AAA Yellow Slurry                                           Ultrasonically Dispersed at Different Temperatures                            Example Temperature During                                                    Number  Ultrasonic Dispersion (°C.)                                                              Mean Diameter (nm)                                  ______________________________________                                        24      20                117; 124; 125                                       25      30                130; 136; 140                                       26      40                111; 116; 116                                       27      50                 83;  86;  88                                       28      60                 76;  80;  80                                       29      70                 68;  70;  69                                       30      80                 80;  81;  82                                       ______________________________________                                    

EXAMPLES 31-34

Examples 31-34 illustrate the effects of striking time and molarity of3,3'-dichlorobenzidine tetrazo on the mean diameters of AAA Yellowslurries, struck at 20° C., treated with 30 percent Duoquad®T, andultrasonically dispersed at 65°-70° C. for 3 hours. Table V provides theresults of Examples 31-34. As can be seen in Table V, striking the AAAYellow over a 50 minute period gave significantly lower mean particlediameters than striking over a 110 minute period. Furthermore, use of amore dilute (0.25 molar) 3,3' dichlorobenzidine tetrazo gave slightlylower mean particle diameters. Mean particle diameter was measured asdescribed in Examples 9-14, and the ultrasonic device utilized was thesame as described in Examples 9-14.

                  TABLE V                                                         ______________________________________                                        Mean Diameters Of AAA Yellow Slurries:                                        Effects of DCB Tetrazo Concentration and Strike Time                                 DCB Tetrazo                                                            Example                                                                              Concentration                                                                             Striking Time                                              Number (molarity)  (minutes)  Mean Diameter (nm)                              ______________________________________                                        31     0.5          50        75; 78; 79                                      32     0.25         50        65; 66; 66                                      33     0.5         110        94; 100; 104                                    34     0.25        110        95; 88; 88                                      ______________________________________                                    

EXAMPLES 35-42

Examples 35-42, the results of which are given in Table VI, illustratethe effects of striking pH and striking time on particulate diameter.The AAA Yellow slurries were struck at 20° C., treated with Duoquad®Tand then ultrasonically dispersed at 65°-70° C. for 4.5 hours. As can beseen in Table VI, a comparison of Examples 36 and 38 with Examples 35and 37 reveals that striking at a constant pH of 5.5 gave significantlylower mean diameters than at a constant pH of 3.5. Examples 40 and 42involve striking in the presence of an acetate buffer, whereby the pHduring striking went from 6.5 to 3.7, as the coupling reactionprogressed. Surprisingly, striking at pH 6.5 to 3.7 (with acetatebuffer) did not give significantly higher mean diameters than strikingat a constant pH of 5.5. Lastly, from Table VI it is apparent thatstriking times of 20 minutes versus 50 minutes did not significantlyaffect mean diameters. Particulate diameter measurements and ultrasonicirradiation were performed as described in Examples 9-14.

                  TABLE VI                                                        ______________________________________                                        Mean Diameters of AAA Yellow Slurries:                                        Effects of Striking pH and Striking Time                                                                Treatment                                                           Striking  Level of  Mean                                      Example                                                                              Striking Time      Duoquad ® T                                                                         Diameter                                  Number pH       (minutes) (wt. %)   (nm)                                      ______________________________________                                        35     3.5      20        50        112; 117; 121                             36     5.5      20        50        84; 88; 89                                37     3.5      50        50        108; 111; 113                             38     5.5      50        50        83; 87; 89                                39     5.5      25        30        83; 85; 88                                40     6.5-3.7  25        30        87; 95; 97                                41     5.5      50        30        79; 83; 88                                42     6.5-3.7  50        30        80; 85; 86                                ______________________________________                                    

EXAMPLES 43-46

Table VII illustrates the effects of striking temperature and strikingtime on particulate diameter. The AAA Yellow slurries were struck with0.25 molar DCB tetrazo, with pH decreasing from 6.0 to 3.5, treated with30 percent Duoquad®T and ultrasonically dispersed at 65°-70° C. for 3hours. A comparison of Examples 43 and 45 with Examples 44 and 46indicates that striking at 25° produced lower mean particulate diametersthan striking at 15° C. Particulate diameter measurements and ultrasonicirradiation were performed as described in Examples 9-14.

                  TABLE VII                                                       ______________________________________                                        Mean Diameters of AAA Strike Slurries:                                        Effects of Striking Temperatures and Times                                    Example                                                                              Striking      Striking  Mean Diameter                                  Number Temp. (°C.)                                                                          Time (min.)                                                                             (nm)                                           ______________________________________                                        43     15            25        113; 120                                       44     25            25        104; 109                                       45     15            45        125; 132                                       46     25            45         88;  93                                       ______________________________________                                    

EXAMPLES 47-52

Table VIII illustrates a comparison of the mean particulate diameter ofAAA Yellow slurry which was freshly struck, treated with 30 percentDuoquad®T, and exposed to ultrasonic irradiation versus the same AAAYellow slurry which was first filtered after striking, following whichthe filtercake was stored for 16 hours at 20° C. in the dark beforebeing reslurried and treated with the Duoquad®T and ultrasonicradiation. The data given in Table VIII indicate that, in general, theslurry from the filtercake procedure gave a mean diameter 10 nanometers(nm) larger than the particulates which were irradiated immediatelyafter striking. Even after extensive (i.e. 9 hours) of ultrasonicdispersion, the slurry from the filtercake procedure gave a meandiameter 10 nm larger than from the slurry. A similar AAA Yellowpresscake stored at 20° C. in the dark for several months gave meandiameters of 329, 363, and 379 nm, much larger than those from slurries.As a result, it has been hypothesized that particulates in a pigmentpresscake may "weld" together, making dispersion (as least ultrasonicdispersion) difficult. Throughout Examples 47-52, particulate diametermeasurements and ultrasonic irradiation were performed as described inExamples 9-14.

                  TABLE VIII                                                      ______________________________________                                        Mean Diameters of AAA Yellow Slurry:                                          Treated Immediately Versus Filtered                                           And Stored as Filtercake, then Treated                                                Hours of                                                                      Ultrasonic                                                            Example Dispersion Mean Diameter (nm) of                                      Number  at 60° C.                                                                         Fresh Slurry                                                                             16 hour Filtercake                              ______________________________________                                        47      1.5        80; 81; 81 95; 98; 98                                      48      3          72; 73; 76 79; 83; 85                                      49      4.5        66; 71; 72 80; 83; 83                                      50      6          66; 69; 71 88; 85; 85                                      51      7.5        --         81; 81; 81                                      52      9          --         79; 81; 81                                      ______________________________________                                    

EXAMPLE 53-59

Table IX illustrates the effects of striking in the presence of three ofthe surfactants claimed on the mean diameters of the AAA Yellowslurries. Unlike the previous Examples, the surfactants were addedbefore striking. Of hundreds of surfactants tested during striking AAAYellow, these three gave the least opaque, most fluid AAA Yellowslurries. In fact, at the 55% level on pigment, the 3.5% AAA Yellowslurries were translucent. At the 85 percent level on pigment, the 3.5AAA Yellow slurries were deep orange solutions of almost completetransparency. From Table IX, the latter slurries contained particles ofmean diameters of 0.02-0.03μ. Striking in the presence of thesesurfactants was the only way of significantly lowering mean diameters ofAAA Yellow slurries below the 0.06-0.10μ obtained with the conventionalstriking conditions shown in Examples 31-46.

A preferred process of the present invention can be carried out by theuse of one or more of the recommended surfactants at a level between 5percent, on weight of pigment, and 95 percent, on weight of pigment.

                  TABLE IX                                                        ______________________________________                                        Mean Diameters of AAA Yellow Slurries:                                        Effects of Striking in Presence of Surfactants                                                                Mean                                          Example Surfactant              Diameter                                      Number  Name            Level (wt. %)                                                                             (nm)                                      ______________________________________                                        53      Duoquad ® T 40          80; 87; 90                                54      Duoquad ® T 55          44; 45; 48                                55      Duoquad ® T 85          32; 33; 33                                56      Duomeen ® TTM                                                                             55          49; 51; 54                                57      Duomeen ® TTM                                                                             85          23; 23; 25                                58      Propoduomeen ® T/13                                                                       55          66; 67; 73                                59      Propoduomeen ® T/13                                                                       85          28; 29; 29                                ______________________________________                                    

EXAMPLES 60-74

A sample of an untreated copper phthalocyanine (CPC) blue presscake wasobtained from Daicolor-Pope Inc. This presscake was known as PC-3004,and was found to contain 42 percent solids. Three 5.95 part aliquots ofthis presscake (i.e. 2.50 parts pigment) were each stirred for 24 hourswith 0.25, 0.50 and 0.75 parts of N-tallowalkyl-N,N,N',N',N'-pentamethyl-1,3-propanediamine dichloride (e.g.Sherex Chemical's Adogen 477) respectively, each mixture being combinedwith enough water to make a total of 50 parts of mixture. Each of theresulting mixtures was then ultrasonically dispersed as described inExamples 9-14, except that 20 g. aliquots in the 1 oz. jars and a 200 WCole-Palmer Branson Ultrasonic cleaner Model B-221 were used. Before thedispersion was subjected to particle size analysis, the dispersion wasdiluted 1:800 with filtered, deionized water, following which thediluted samples were placed in the sample cuvettes and ultrasonicallydispersed for two minutes. The cuvettes were allowed to stand in the N4sample chamber for 10 minutes before measurements were started. Table Xprovides results for these Examples. As can be seen in Table X, the CPCBlue was deflocculated to 100-110 nm after 5 hours of ultrasonicdispersion at 60° C. Furthermore, additional ultrasonic dispersion didnot further decrease the resulting mean particle diameter. Also,increasing the level of Adogen 477 from 10 weight percent to 30 weightpercent did not significantly change the resulting mean particlediameter.

                  TABLE X                                                         ______________________________________                                        Mean Diameters of CPC Blue Slurries                                           Treated and Ultrasonically Dispersed Under Various Conditions                         Weight      Time of                                                           Percent of  Ultrasonic                                                Example Adogen 477  Dispersion at                                                                             Mean Diameter                                 Number  On Pigment  60° C. (Hrs)                                                                       (nm)                                          ______________________________________                                        60      10          1           132; 136; 139                                 61      10          3           110; 115; 118                                 62      10          5           105; 108; 112                                 63      10          7           100; 105; 109                                 64      10          10          101; 105; 104                                 65      20          1           124; 135; 142                                 66      20          3           113; 121; 123                                 67      20          5           105; 112; 112                                 68      20          7           106; 113; 111                                 69      20          10          104; 111; 111                                 70      30          1           125; 131; 134                                 71      30          3           113; 122; 120                                 72      30          5           107; 110; 113                                 73      30          7           108; 111; 109                                 74      30          10          105; 110; 109                                 ______________________________________                                    

EXAMPLES 75-78

The procedure of Examples 60-74 was again followed in general, exceptthat the surfactant was utilized at 20 percent (on a pigment weightbasis). Furthermore, Examples 77 and 78 utilized Mazer Chemical'snonionic Macol CSA-10 (a hexadecyl/octadecyl alcohol adduct with 10moles of ethylene oxide). Also, in Examples 76 and 78, the ultrasonicirradiation was carried out at 20°-25° C. The Adogen 477 producedapproximately the same mean particle diameter at 20° C. as at 60° C.,whereas the Macol CSA-10 gave a much lower mean diameter at 20° C. thanat 60° C. However, even at 20° C. the Adogen 477 enabled deflocculationto lower mean particle diameters than did Macol CSA-10.

                  TABLE XI                                                        ______________________________________                                        Mean Diameter of CPC Blue Slurry                                              Treated and Ultrasonically Dispersed Under Various Conditions                               Ultrasonic                                                                    Dispersion                                                                    Conditions                                                              Surfactant  Tempera-                                                  Example (20% on weight                                                                            ture     Time  Mean Particle                              Number  pigment)    (°C.)                                                                           (hours)                                                                             Diameter (nm)                              ______________________________________                                        75      Adogen 477  60       10    104; 108; 110                              76      Adogen 477  20       10    104; 111; 112                              77      Macol CSA-10                                                                              60       10    155; 163; 169                              78      Macol CSA-10                                                                              20       10    119; 125; 126                              ______________________________________                                    

EXAMPLES 79-94

The procedure of Examples 75-78 was repeated, except that several othernonionic surfactants with HLB (Hydrophilic-Lipophilic Balance) of11.1-12.4 were substituted for the Macol CSA-10. The temperature of thewater in the ultrasonic bath was maintained at 20°-25° C. byintermittent additions of ice. Table XII provides the results of theseexperiments. BRIJ 76 (manufactured by ICI), the adduct of octadecylalcohol with 10 moles of ethylene oxide, gave somewhat lower meandiameters than Macol CSA-10, but still 10-20 nm higher than with Adogen477. The other nonionic surfactants listed in Table XII gave stillhigher mean diameters. Furthermore, none of the nonionic surfactantsproduced the low mean diameters achieved by the cationic N-tallowalkyl-N,N,N'N'N'-pentamethyl-1,3-propanediamine dichloride (Adogen 477).

                  TABLE XII                                                       ______________________________________                                        Mean Diameters of CPC Blue Slurry Treated                                     And Ultrasonically Dispersed at 20° C. for 5 or 10 Hours                       Surfactant Used                                                               (20 wt. %                                                             Example on pigment)   Ultrasonic Mean Particle                                Number  Name      HLB     Time (hrs)                                                                             Diameter (nm)                              ______________________________________                                        79      Macol     12.6     5       139; 153; 145                                      CSA-10                                                                80      Macol     12.6    10       132; 134; 136                                      CSA-10                                                                81      BRIJ 76   12.4     5       129; 137; 137                              82      BRIJ 76   12.4    10       114; 121; 127                              83      BRIJ 96   12.4     5       127; 139; 142                              84      BRIJ 96   12.4    10       126; 135; 137                              85      Chemax    12.6    10       156; 154; 157                                      CO-36                                                                 86      Triton    12.4    10       142; 178; 248                                      X-114                                                                 87      Chemax    12.0    10       388; 501; 657                                      E-400MS                                                               88      Pluronic  12.0    10       273; 319; 362                                      L43                                                                   89      Chemax    11.8    10       256; 256; 254                                      E-400MO                                                               90      Chemax    11.7    10       203; 201; 203                                      CO-30                                                                 91      Chemax    11.5    10       200; 199; 195                                      TO-10                                                                 92      MYRJ 45   11.1    10       465; 707; 796                              93      Sorbax    11.0    10       150; 162; 399                                      PTO-20                                                                94      Pluronic  11.0    10       283; 566; 1270                                     L63                                                                   ______________________________________                                    

EXAMPLES 95-110

The procedure of Examples 79-94 was followed, except that threeamine-containing surfactants (dissolved in dilute acetic acid andadjusted to pH 5.3-6.0 with acetic acid) were substituted for thenonionic surfactants. Table XIII shows that these cationic surfactantsproduced lower mean diameters than the nonionic surfactants of Examples79-94 and were surprisingly almost as effective deflocculants as Adogen477. Furthermore, one nonionic surfactant (Chemal OA-9) produced meandiameters essentially as low as the three cationic surfactants. Thissurfactant, with an HLB (11.9) in the middle of the range of the lesseffective deflocculants of Table XII, was surprisingly effective. It wassurprisingly found that surfactants with only one more mole of ethyleneoxide (i.e. 10 vs. 9 moles EO), such as BRIJ 96, BRIJ 76, Macol CSA-10and Chemax TO-10, were not nearly as effective deflocculants. Also,changing the connecting group between the 9-octadecenyl group and the 9mole polyethylene oxide group from the ether connecting group of ChemalOA-9 to the ester group of Chemax E-400MO had a surprisingly deleteriouseffect on deflocculating efficiency (compare Example 110 vs. 89). Therewas a surprising deflocculating efficiency of the combination of a C₁₈hydrocarbon tail connected by an ether group to a polyethylene glycolhead made with 9 moles ethylene oxide. These three cationic surfactants,together with one nonionic surfactant, were almost as effective asAdogen 477 (Compare Example 76 against Examples 98, 102, 106 and 110).

                  TABLE XIII                                                      ______________________________________                                        Mean Diameters of CPC Blue Slurry Treated and                                 Ultrasonically Dispersions at 20° C. for Various Times                         Surfactant Used                                                                             Ultrasonic                                              Example At 20 wt. percent                                                                           Dispersion Mean Diameter                                Number  on Pigment    Time (hrs) (nm)                                         ______________________________________                                         95     Duomeen TTM   3          114; 120; 118                                 96     Duomeen TTM   5          114; 118; 116                                 97     Duomeen TTM   7          113; 115; 114                                 98     Duomeen TTM   10         111; 109; 112                                 99     Propoduomeen T/13                                                                           3          124; 126; 128                                100     Propoduomeen T/13                                                                           5          114; 118; 123                                101     Propoduomeen T/13                                                                           7          119; 116; 122                                102     Propoduomeen T/13                                                                           10         112; 115; 114                                103     Jetamine TET  3          129; 124; 129                                104     Jetamine TET  5          121; 120; 118                                105     Jetamine TET  7          113; 118; 118                                106     Jetamine TET  10         113; 118; 118                                107     Chemal OA-9   3          123; 127; 129                                108     Chemal OA-9   5          117; 115; 113                                109     Chemal OA-9   7          119; 122; 122                                110     Chemal OA-9   10         115; 119; 120                                ______________________________________                                    

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:
 1. A method of dispersing anorganic pigment, the method comprising the steps of:(A) adding asurfactant to an aqueous slurry of an organic pigment, the surfactantbeing selected from the group consisting of:1. an acidic salt ofN-alkyl-N,N'-trimethyl-1,3-propanediamine, wherein the alkyl groupcontains from about 12 to about 22 carbon atoms, as well as triethyl andtripropyl derivatives thereof;
 2. an acidic salt ofN-alkyl-N,N',N'-tris(2-hydroxy propyl)-1,3-propanediamine, wherein thealkyl group contains from about 12 to about 22 carbon atoms, as well as2-hydroxyethyl and 2-hydroxybutyl derivatives thereof;
 3. a quaternarysalt of N-alkyl-N,N,N',N',N'-pentamethyl-1,3-propanediamine, wherein thealkyl group contains from about 12 to 22 carbon atoms, as well aspentaethyl and pentapropyl derivatives thereof;
 4. an acidic salt ofN-alkyl-N'-(3-aminopropane)-1,3-propanediamine, wherein the alkyl groupcontains from about 12 to about 22 carbon atoms, as well as tetramethyl,tetraethyl, tetrapropyl, tetrakis(2-hydroxy ethyl), tetrakis(2-hydroxypropyl), tetrakis(2-hydroxybutyl), heptamethyl, heptaethyl, andheptapropyl derivatives thereof;
 5. an acidic salt ofN-alkyl-N-(3-aminopropane)-1,3-propanediamine, wherein the alkyl groupcontains from about 12 to about 22 carbon atoms, as well as tetramethyl,tetraethyl, tetrapropyl, tetrakis(2-hydroxyethyl),tetrakis(2-hydroxypropyl), tetrakis-(2-hydoxy- butyl), heptamethyl,heptaethyl, and heptapropyl derivatives thereof;
 6. an acid salt ofN-(N-alkyl-3-aminoprpane)-N'-(3-aminopropane)-1,3-propanediamine,wherein the alkyl group contains about 12 to about 22 carbon atoms, aswell as pentamethyl, pentaethyl, pentapropyl, pentakis (2-hydroxyethyl),pentakis(2-hydroxypropyl), pentakis (2-hydroxybutyl), nonamethyl,nonaethyl, and nonapropyl derivatives thereof; and
 7. apoly(ethyleneoxide) ether of an 18 carbon alcohol having 9 units ofethylene oxide thereon; and (B) dispersing the pigment by subjecting theslurry to ultrasonic radiation.
 2. The method as described in claim 1,wherein the surfactant is selected from the group consisting of:1. anacidic salt of N-alkyl-N,N',N'-trimethyl-1,3-propanediamine, wherein thealkyl group contains from about 12 to about 22 carbon atoms, as well astriethyl and tripropyl derivatives thereof;
 2. an acidic salt ofN-alkyl-N',N'-tris(2-hydroxypropyl)-1,3-propanediamine, wherein thealkyl group contains from about 12 to about 22 carbon atoms, as well as2-hydroxyethyl and 2-hydroxybutyl derivatives thereof;
 3. a quaternarysalt of N-alkyl-N,N,N',N',N'-pentamethyl-1,3-propanediamine, wherein thealkyl group contains from about 12 to about 22 carbon atoms, as well aspentaethyl and pentapropyl derivatives thereof;
 4. an acidic salt ofN-alkyl-N'-(3-aminopropane)-1,3-propanediamine, wherein the alkyl groupcontains from about 12 to about 22 carbon atoms, as well as tetramethyl,tetraethyl, tetrapropyl, tetrakis(2-hydroxyethyl),tetrakis(2-hydroxypropyl), tetrakis(2-hydroxybutyl), heptamethyl,heptaethyl, and heptapropyl derivatives thereof;
 5. an acidic salt ofN-alkyl-N-(3-aminopropane)-1,3-propanediamine, wherein the alkyl groupcontains from about 12 to 22 carbon atoms, as well as tetramethyl,tetraethyl, tetrapropyl, tetrakis(2-hydroxyethyl),tetrakis(2-hydroxypropyl), tetrakis(2-hydroxybutyl), heptamethyl,heptaethyl, and heptapropyl derivatives thereof;
 6. an acidic salt ofN-(N-alkyl-3-aminopropane)-N'-(3-aminopropane)-1,3-propanediamine,wherein the alkyl group contains from about 12 to about 22 carbon atoms,as well as pentamethyl, pentaethyl, pentapropyl,pentakis(2-hydroxyethyl), pentakis(2-hydroxypropyl),pentakis(2-hydroxybutyl), nonamethyl, nonaethyl, and nonapropylderivatives thereof.
 3. The method as described in claim 1 wherein thedispersion of the pigment particles is carried out at a temperaturebetween 15° C. and the boiling point of the pigment slurry.
 4. Themethod as described in claim 1 wherein the dispersing step is carriedout for a period less than 5 hours.
 5. The method as described in claim1 wherein the dispersing step is carried out for a period between 30minutes and 5 hours.
 6. The method as described in claim 1 wherein thesurfactant is added to the pigment slurry in an amount between 2percent, on weight of pigment, and 100 percent, on weight of pigment. 7.The method as described in claim 1 wherein the surfactant is added tothe pigment slurry in an amount between 5 percent, on weight of pigmentand 85 percent on weight of pigment.
 8. The method as described in claim1 wherein the surfactant is added to the pigment slurry in an amountbetween 10 percent, on weight of pigment, and 30 percent, on weight ofpigment.
 9. The method as described in claim 1 wherein the pigment is asubstantially transparent pigment and the surfactant is added in anamount between 10 percent, on weight of pigment, and 30 percent, onweight of pigment.
 10. The method as described in claim 1 wherein thepigment is a substantially opaque pigment and the surfactant is added inan amount between 5 percent, on weight of pigment, and 10 percent, onweight of pigment.
 11. The method as described in claim 1 wherein thesurfactant is present in an amount between 50 percent, on weight ofpigment, and 90 percent, on weight of pigment, and the dispersingprocess is carried out during the striking of the pigment.
 12. Themethod as described in claim 1 wherein the pigment is one or moremembers selected from the group consisting of nitroso pigments, disazopigments, disazo condensation pigments, basic dye pigments, alkali bluepigments, Peacock blue lake pigments, phloxine pigments, quinacridonepigments, lake pigments of Acid Yellow 1 and 3, carbazole dioxazineviolet pigments, alizarine lake pigments, vat pigments, phthalocyaninepigments, carmine lake pigments, tetrachloroisoindolinone pigments, andcarbon black pigments.
 13. The method as described in claim 1 whereinthe pigment is one or more members selected from the group consisting ofmonoazo, disazo, phthalocyanine, and carbon black pigments.
 14. Themethod as described in claim 1 wherein the organic pigment is selectedfrom the group consisting of Pigment Yellow 12, Pigment Blue 15, PigmentBlack 7, and Pigment Red
 49. 15. The method as described in claim 2wherein the dispersion of the pigment particles is carried out at atemperature between 15° C. and the boiling point of the pigment slurry.16. The method as described in claim 2 wherein the dispersing step iscarried out for a period less than 5 hours.
 17. The method as describedin claim 2 wherein the dispersing step is carried out for a periodbetween 30 minutes and 5 hours.
 18. The method as described in claim 2wherein the surfactant is added to the pigment slurry in an amountbetween 2 percent, on weight of pigment, and 100 percent, on weight ofpigment.
 19. The method as described in claim 2 wherein the surfactantis added to the pigment slurry in an amount between 5 percent, on weightof pigment and 85 percent on weight of pigment.
 20. The method asdescribed in claim 2 wherein the surfactant is added to the pigmentslurry in an amount between 10 percent, on weight of pigment, and 30percent, on weight of pigment.
 21. The method as described in claim 2wherein the pigment is one or more members selected from the groupconsisting of nitroso pigments, disazo pigments, disazo condensationpigments, basic dye pigments, alkali blue pigments, Peacock blue lakepigments, phloxine pigments, quinacridone pigments, lake pigments ofAcid Yellow 1 and 3, carbazole dioxazine violet pigments, alizarine lakepigments, vat pigments, phthalocyanine pigments, carmine lake pigments,tetrachloroisoindolinone pigments, and carbon black pigments.
 22. Themethod of claim 2 wherein the pigment is one or more members selectedfrom the group consisting of monoazo, disazo, phthalocyanine, and carbonblack pigments.
 23. The method of claim 2 wherein the organic pigment isselected from the group consisting of Pigment Yellow 12, Pigment Blue15, Pigment Black 7, and Pigment Red
 49. 24. The method as described inclaim 2 wherein the pigment is a substantially transparent pigment andthe surfactant is added in an amount between 10 percent, on weight ofpigment, and 30 percent, on weight of pigment.
 25. The method asdescribed in claim 2 wherein the pigment is a substantially opaquepigment and the surfactant is added in an amount between 5 percent, onweight of pigment, and 10 percent, on weight of pigment.
 26. The methodas described in claim 2 wherein the surfactant is present in an amountbetween 50 percent, on weight of pigment, and 90 percent, on weight ofpigment, and the dispersing process is carried out during the strikingof the pigment.